Yeah, my brainfart. 
TRIACS are OFF until we trigger them on. So Gtech needs to invert the program logic. There are though some more complicated MOSFET-TRIACS, SCS and similar which do allow on&off control.
Yeah, my brainfart. TRIACS are OFF until we trigger them on. So Gtech needs to invert the program logic. There are though some more complicated MOSFET-TRIACS, SCS and similar which do allow on&off control.